Pipeline transportation of heavy crude oil

ABSTRACT

A method for transporting heavy crude oil through a pipeline which involves introducing into a pipeline or well-bore with the viscous hydrocarbons an aqueous solution containing (1) a sulfonate surfactant, (2) a rosin soap or a naphthenic acid soap and, optionally (3) a coupling agent whereby there is spontaneously formed a low viscosity, salt tolerant, oil-in-water emulsion.

This is a continuation-in-part of application Ser. No. 664,740, filedMar. 8, 1976, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improved method for transporting viscoushydrocarbons through a pipeline or well-bore. More particularly, thisinvention relates to the introduction into a pipeline of a viscoushydrocarbon or mixture of hydrocarbons together with an aqueous solutionof an organic sulfonate, a rosin soap or a naphthenic acid soap and,optionally, a coupling agent such as ethylene glycol monobutyl ether,whereby a low viscosity, salt-tolerant, oil-in-water emulsion is formedwhich facilitates movement of the heavy oils through the pipeline. Ifdesired, the solution may contain an added alkalinity agent.

2. Description of the Prior Art

The transportation of heavy crudes by pipeline is difficult because oftheir low mobility and high voscosity. The usual methods to facilitatethe flow of heavy crudes have included cutting them with lighterfractions of hydrocarbons. However, the procedures involve the use ofrelatively large amounts of expensive hydrocarbon solvents to transporta relatively cheap product. The practice also necessarily requires theavailability of the cutting hydrocarbon solvents which, in someinstances, is inconvenient.

Another method to assist the flow of hydrocarbons in pipeline is theinstallation of heating equipment at frequency intervals along thepipeline whereby the crude is heated to reduce its viscosity and therebyfacilitate its transport. Heaters employed for this purpose can beoperated by withdrawing some of the crude being transported for use afuel. However, this procedure may result in the loss of as much as 15 to20% of the crude being transported.

Other methods to facilitate transport of heavy crudes have employedthermal viscosity breaking, which, however, produces substantial amountsof gas.

It is known that substantial amounts of water may be introduced into apipeline containing a stream of viscous crude flowing therethrough toreduce the drag on the stream and thus facilitate the flow through thepipeline. This has been done by the addition of water together withcrude into the pipeline such that a water-in-oil emulsion is formed.

It is thus an object of the present invention to provide a transportmethod for viscous crudes which are difficult to emulsify especially inthe presence of water with substantial salt content whereby they can bemore easily transported by pipeline at a high throughput rate.

SUMMARY OF THE INVENTION

This invention relates to a method for transporting viscous hydrocarbonssuch as heavy crude oils in which the hydrocarbon together with anaqueous solution of (1) a sulfonate surfactant selected from the groupconsisting of alkyl sulfonates, and ethoxylated alkyl or alkarylsulfonates, (2) a rosin soap or a naphthenic soap and, optionally, (3) acoupling agent such as a glycol mono ether, and/or an alkalinity agentis introduced into the pipeline with mixing. During the mixing operationan oil-in-water emulsion is formed which is stable in hard water andsalt tolerant.

DESCRIPTION OF THE INVENTION

In this invention the aqueous solution added to the viscous hydrocarbonwill generally range from a minimum of about 15 percent by volume basedon the volume of the hydrocarbon introduced into the pipeline up to amaximum of about 35 percent or more by volume with the preferred amountbeing about 20 to about 30 percent by volume on the same basis. In theaqueous solution the concentration of the sulfonate surfactant willrange from about 0.01 to about 2.0 weight percent; the rosin soap or thenaphthenic acid soap from about 0.01 to about 1.8 weight percent and theoptionally present coupling agent of from 0.02 to about 1.0 weightpercent. Mixtures of the above-mentioned ingredients may also be used inthe process of this invention.

Sulfonate type surfactants which may be utilized in the process of thisinvention include alkyl sulfonates and alkoxylated alkyl or alkarylsulfonates.

One type of useful sulfonates includes compounds of the followinggeneral formula:

    R -- SO.sub.3 -- Y                                         (I)

wherein R is an alkyl radical, linear or branched, having 5 to 25 and,preferably, from 8 to 14 carbon atoms and Y is a monovalent cation suchas sodium, potassium or the ammonium ion. For example, if R is lineardodecyl and Y is the ammonium radical, then the compound is ammoniumdodecyl sulfonate.

Another group of sulfonate surfactants which are especially suitableincludes compounds of the formula:

    R.sub.a O (CH.sub.2 CH.sub.2 O).sub.x CH.sub.2 CH.sub.2 SO.sub.3 M, (II)

wherein R_(a) is selected from the group consisting of alkyl of from 8to 26 carbon atoms and ##STR1## wherein R_(b) is selected from the groupconsisting hydrogen and alkyl of from 1 to 5 carbon atoms, R_(c) isselected from the group consisting of hydrogen and alkyl of from 1 to 5carbon atoms and x is an integer of from 1 to 20 and M is a metalliccation such as sodium or potassium or ammonium ion.

One method of preparing the Type II sulfonates described above is asfollows. A polyethoxylated alkanol is first reacted with sulfurousoxychloride (SOCl₂) in order to replace the terminal hydroxyl group witha chlorine, which may then be reacted with sodium sulfite, Na₂ SO₃, toform the desired polyethoxylated alcohol sulfonate.

The above mode of formulating the desired sulfonate salt of thepolyethoxylated alcohol by first forming the halide and then reacting itwith sulfite (the Strecker reaction) is believed to be the preferredmethod of synthesizing the compound of the present invention. Anotherpossible route involves forming the sulfate salt and then reacting thesulfate salt with sodium sulfite. Drastic reaction conditions arenecessary to force this latter reaction to go, however, e.g., about 200°C. for at least 12 hours.

Type II sulfonates where R_(a) is: ##STR2## can be prepared for example,by reacting the corresponding quinoline sulfonic acid starting materialwith, for example, phosphorus pentachloride to form the quinolinesulfonyl chloride which in turn may then be reacted with a polyethyleneglycol of suitable molecular weight to yield the ethoxylated sulfonylquinoline derivative. Preparation of such ethoxylated derivatives ismore completely described in U.S. Pat. No. 3,731,741 which isincorporated herein in its entirety. Once the ethoxylated quinolineprecursor has been prepared it can be sulfonated in the mannerpreviously described to yield the corresponding sulfonate of theformula: ##STR3## wherein R_(b), R_(c), x and M have the same meaning asset out above.

Typical Type II A sulfonates which are useful in the method of thisinvention include: ##STR4##

A wide variety of rosin soaps may be utilized in the method of thisinvention as exemplified by sodium abietate, potassium abietate,ammonium abietate, etc. Mixtures of these same rosin soaps may beemployed if desired. Suitable naphthenic acid soaps include sodiumnaphthenate, potassium naphthenate, ammonium naphthenate, etc. andmixtures thereof.

Glycol monoalkyl ethers useful in the process of this invention includecompounds of the formula:

    R.sub.c O(R.sub.d O).sub.m H,

wherein R_(c) is alkyl of from 1 to 6 carbon atoms, R_(d) is alkylene offrom 2 to 3 inclusive carbon atoms and m is an integer of from 1 to 3inclusive. Examples of glycol monoalkyl ethers suitable for use in thisinvention include ethylene glycol monometyl ether, diethylene glycolmonoethyl ether, triethylene glycol monopropyl ether, propylene glycolmonomethyl ether, dipropylene glycol monoethyl ether, triethylene glycolmonobutyl ether, tetrapropylene glycol monoethyl ether, etc.

The alkaline agent, if employed, is selected from the group consistingof the alkali metal hydroxides as exemplified by sodium hydroxide,potassium hydroxide, mixtures thereof, etc. which are generally added tothe aqueous solution in an amount of from about 0.05 to about 1.0 weightpercent.

In another aspect this invention relates to an oil-in-water emulsioncomprising a hydrocarbon such as crude oil including heavy crude oil,diesel oil, fuel oil, propane, propane-butane mixtures as exemplified byLPG, etc., and as the aqueous phase an aqueous solution comprising about0.01 to 2.0 percent by weight of the sulfonate surfactant and about 0.01to about 1.8 percent by weight of a soap selected from the groupconsisting of rosin soaps, naphthenic acid soaps and mixtures. Suchemulsions are useful in a wide variety of other applications such as insecondary recovery operations, etc. These emulsions are prepared bymixing together the hydrocarbon and the aqueous solution. The amount ofthe aqueous solution added to the hydrocarbon will generally range froma minimum of about 15 percent by volume based on the volume of thehydrocarbon up to a maximum of about 35 percent or more by volume withthe preferred amount being about 20 to about 30 percent by volume on thesame basis. Optionally, the aqueous solution may contain from about 0.02to about 1.0 weight percent of a coupling agent of the type previouslydescribed and/or an alkalinity agent also of the type previouslydescribed in an amount of from 0.05 to about 1.0 weight percent.

In another embodiment of this invention relates to the above-describedaqueous solutions employed to prepare oil-in-water emulsions of thisinvention and which are useful in a wide variety of other applicationssuch as cleaning the well bore of injection wells to permit increasedinjection rates into the formation in secondary recovery operations.

The following examples illustrate embodiments of this invention whichare to be considered not limitative:

EXAMPLE I

An aqueous solution containing 0.8 weight percent of sodium dodecylsulfonate, 0.10 weight percent of potassium abietate, and about 0.35weight percent of diethylene glycol monobutyl ether is prepared byadding with mixing the above-mentioned ingredients to water havingsalinity of about 1.73 weight percent at a temperature of about 25° Cafter which the thus-prepared solution is introduced with mixing into alarge diameter pipeline together with sufficient heavy California crudefrom Orange County, California to give an oil-in-water emulsion in whichthe amount of aqueous solution is about 22 percent by volume based onthe volume of the crude. The horsepower requirement for transporting theformed oil-in-water emulsion through the pipeline at the rate of 2000barrels per day is found to be substantially less than the horsepowerrequirement for transporting the same volume of this California heavycrude under the same conditions.

EXAMPLE II

An aqueous solution comprising about 0.13 weight percent ammoniumtetrodecyl sulfonate, 0.20 weight percent of a sulfonate of the formula:##STR5## 0.10 weight percent sodium abietate, 0.15 weight percentpotassium naphthenate and about 0.10 weight percent sodium hydroxide isformed by mixing together at a temperature of about 25° C. theabove-named ingredients with brine having a salinity of about 1.77weight percent. The thus-formed aqueous solution is introduced into apipeline together with Hunton crude, Hunton County, Oklahoma to give anoil-in-water emulsion in which the volume percent of the aqueoussolution based on the volume of the crude is about 22 percent. Anappreciable saving in horsepower through the pipeline over therequirement for the same amount of Hunton crude under the sameconditions is achieved.

Another embodiment of this invention relates to a process for therecovery of hydrocarbons from subterranean hydrocarbon-bearingformations having in communication therewith at least one injection welland one production well in which there is injected into the formationvia the injection well an aqueous solution of the type previouslydescribed which comprises a sulfonate surfactant, a rosin or naphthenicacid soap and, optionally, a coupling agent, and hydrocarbons arerecovered via the production well.

In recovering oil from oil-bearing reservoirs it usually is possible torecover only a minor part of the original oil in place by the primaryrecovery methods which utilize the natural forces present in thereservoir. As a result, a variety of supplemental recovery techniqueshave been utilized to increase the recovery of oil from subterraneanhydrocarbon-bearing reservoirs or formations. Although thesesupplemental techniques are commonly referred to as secondary recoveryoperations in fact they may be primary or tertiary in sequence ofemployment. In such techniques, a fluid is introduced into the formationin order to displace the oil therein to a suitable production systemthrough which the oil may be withdrawn to the surface of the earth.Examples of displacing mediums include gas, aqueous liquids such asfresh water or brine, oil-miscible liquids such as butane, or a waterand oil-miscible liquid such as alcohol. Generally, the most promisingof the secondary recovery techniques is concerned with the injectioninto the formation of an aqueous flooding medium either alone or incombination with other fluids.

This embodiment of the invention relates to a method for recoveringhydrocarbons from a subterranean hydrocarbon-bearing formation having incommunication therewith at least one injection well and one productionwell comprising:

(a) injecting into the said formation through the said injection well anaqueous solution comprising a sulfonate surfactant and a rosin ornaphthenic acid soap,

(b) forcing the said aqueous solution through the formation, and

(c) recovery hydrocarbons through the said production well.

Any of the type I, II, and II-A sulfonates previously described may beemployed in the aqueous solution of step (a) above. Suitable rosin soapsinclude, for example, sodium abietate, potassium abietate, etc. andmixtures thereof. Useful naphthenic acid soaps include materials such assodium, potassium and ammonium naphthenates. Coupling agents, ifutilized in the aqueous solution may be, for example, any of the glycolmonoalkyl ethers as defined previously. An alkalinity agent such assodium hydroxide or potassium hydroxide may, if desired, be added to theaqueous solution.

The aqueous solution utilized in the recovery process will compriseabout 0.01 to 2.0 percent by weight of the sulfonate surfactant, about0.01 to about 1.8 percent by weight of the soap, about 0.02 to about 1.0weight percent of the optionally included coupling agent and/or analkalinity agent in an amount of from 0.05 to about 1.0 weight percent.

The process of this invention can be carried out with a wide variety ofinjection and production systems which will comprise one or more wellspenetrating the producing strata or formation. Such wells may be locatedand spaced in a variety of patterns which are well-known to thoseskilled in the art. For example, the so-called "line flood" pattern maybe used, in which case the injection and producing systems are composedof rows of wells spaced from one another. The recovery zone, i.e., thatportion of the production formation from which hydrocarbons aredisplaced by the drive fluid to the production system, in this instancewill be that part of the formation underlying the area between thespaced rows. Another pattern which is frequently used is the so-called"circular flood" in which the injection system comprises a centralinjection well while the production system comprises a plurality ofproduction wells spaced about the injection well. Likewise, theinjection and production systems each may consist of only a single welland here the recovery zone will be that part of the producing strataunderlying an elliptical-like area between the two wells which issubject to the displacing action of the aqueous drive fluid. For a moreelaborate description of such recovery patterns reference is made toUren, L. C., Petroleum Production Engineering-Oil Field Exploitation,Second Edition, McGraw Hill Book Company, Inc., New York, 1939, and toU.S. Pat. Nos. 3,472,318 and 3,476,182.

In conducting the process of this invention, the aqueous solutionprepared as described above is forced, usually via a suitable pumpingsystem, down the well bore of an injection well and into the producingformation through which it is then displaced together with hydrocarbonsof the formation in the direction of a production well.

The formation may be treated continuously with the aqueous solution orsuch treatment may be temporary. If desired, however, after a time,conventional flooding may be resumed. The aqueous solution of thisinvention also may be applied in a modified water flood operation inwhich there is first injected into the well bore a slug of the aqueoussolution which is forced under pressure into the subterranean formation.This first step is then followed by a similar injection step wherein aslug of an aqueous drive fluid, such as water, is injected, which isthereafter followed by a repetition of the two steps. This sequence maybe repeated to give a continuous cyclic process. The size of the slugsmay be varied within rather wide limits and will depend on a number ofconditions, including the thickness of the formation, itscharacteristics and the conditions for the subsequent injection of theaqueous drive medium.

EXAMPLE III

Through a water injection well drilled into a limestone formation thereis displaced under pressure down the tubing and into the formation atthe rate of 75 barrels per day an aqueous solution of 0.09 weightpercent of potassium decyl sulfonate, 0.15 weight percent of a sulfonateof the formula: ##STR6## 0.20 weight percent of potassium naphthenateand about 0.05 weight percent of sodium hydroxide formed by mixingtogether at a temperature of about 25° C the above-named ingredientswith brine having a salinity of about 1.18 weight percent. After about15 days the production of hydrocarbons is substantially increased overthat obtained when brine alone is utilized as the drive fluid.

What is claimed is:
 1. In the transportation of viscous hydrocarbons bypipeline, the improvement which comprises forming an oil-in-wateremulsion by introducing into the pipeline with said hydrocarbons anaqueous solution comprising about 0.01 to about 2.0 percent by weight ofsurfactant of the formula: ##STR7## wherein R_(b) is selected from thegroup consisting of hydrogen and alkyl of from 1 to 5 carbon atoms,R_(c) is selected from the group consisting of hydrogen and alkyl offrom 1 to 5 carbon atoms, x is an integer of from 1 to 20 and M is amonovalent cation selected from the group consisting of sodium,potassium, lithium and ammonium, and about 0.01 to about 1.8 percent byweight of a soap selected from the group consisting of rosin soaps andnaphthenic acid soaps and mixtures thereof.
 2. The method of claim 1wherein the said rosin soaps is selected from the group consisting ofsodium abietate, potassium abietate, lithium abietate, ammonium abietateand mixtures thereof.
 3. The method of claim 1 wherein the saidnaphthenic soap is selected from the group consisting of sodiumnaphthenate, potassium naphthenate, lithium naphthenate, ammoniumnaphthenate and mixtures thereof.
 4. The method of claim 1 wherein thesaid aqueous solution contains from 0.02 to about 1.0 weight percent ofa coupling agent of the formula:

    R.sub.c O(R.sub.d O).sub.m H,

wherein R_(c) is alkyl of from 1 to 6 carbon atoms, R_(d) is alkylene offrom 2 to 3 inclusive carbon atoms and m is an integer of from 1 to 3inclusive.
 5. In the transportation of viscous hydrocarbons by pipeline,the improvement which comprises forming an oil-in-water emulsion byintroducing into the pipeline with said hydrocarbons an aqueous solutioncomprising from about 0.01 to about 2.0 weight percent of a surfactantof the formula ##STR8## wherein R_(b) is selected from the groupconsisting of hydrogen and alkyl of from 1 to 5 carbon atoms, R_(c) isselected from the group consisting of hydrogen and alkyl of from 1 to 5carbon atoms, x is an integer of from 1 to 20 and M is a monovalentcation selected from the group consisting of sodium, potassium, lithiumand ammonium, and from about 0.01 to about 1.8 weight percent of a soapselected from the group consisting of a rosin soap and a naphthenic acidsoap, from about 0.02 to about 1.0 weight percent of a coupling agent ofthe formula:

    R.sub.c O(R.sub.d O).sub.m H,

wherein R_(c) is alkyl of from 1 to 6 carbon atoms, R_(d) is alkylene offrom 2 to 3 inclusive carbon atoms and m is an integer of from 1 to 3inclusive and from 0.05 to about 1.0 weight percent of an alkalinityagent selected from the group consisting of sodium hydroxide andpotassium hydroxide.